The maximum concentration of ozone is found in which of the following?

The correct answer is C) Stratosphere. Ozone is concentrated in the stratosphere, roughly 15 to 35 km above the surface, with the peak density around 20 to 25 km. This is the ozone layer that absorbs most of the Sun's harmful UV-B and UV-C radiation. Ozone forms here when UV light splits oxygen molecules, and the O2 and O3 then keep converting back and forth.

• Troposphere (A): Ozone is present near the surface, but only a small fraction of total ozone lies here. Ground-level ozone is a pollutant formed from vehicular and industrial emissions, not the protective layer.
• Mesosphere (B): Some ozone exists here, but its concentration is far lower than in the stratosphere.
• Exosphere (D): The outermost layer is extremely thin, so ozone is practically absent.

The core concept is the stratospheric ozone layer and its role in shielding life. For Mains GS-III (environment), link this to the Vienna Convention (1985) and the Montreal Protocol (1987), which phased out ozone-depleting substances like CFCs, and to the Kigali Amendment (2016) on HFCs.

Trap: Aspirants often pick troposphere because they associate ozone with smog and pollution. The question asks about the highest concentration of ozone in the atmosphere, which is the stratosphere.